Larger Image Figure 3. Ethidium inhibits the second phase of chromatin decondensation. (A) Sperm nuclei were incubated for 60 min in control (Ctl) or 100 µM ethidium (EB) treated extracts, and decondensation was monitored by staining DNA with Hoechst 33‱258. (B) Sperm decondensation in the absence (Ctl) or presence of 100 μM ethidium (EB) was monitored by incubating sperm nuclei in IEE, isolating them and staining directly with Hoechst 33‱258, at indicated time-points. (C) Sperm nuclei (or without DNA, lane 3) were incubated in buffer alone (lanes 4 and 7) or in interphase egg extract, in the absence (lanes 2, 3, 4 and 5) or in presence of EB, at 100 μM (lanes 6, 7 and 10), 50 μM (lane 9) or 25 μM (lane 8), without (lanes 2 and 6) or with micrococcal nuclease, for 10 min. Nucleosome assembly was monitored by gel electrophoresis; lane 1:100 bp DNA ladder. Image published in: Krasinska L and Fisher D (2009) © 2009 The Author(s). Creative Commons Attribution-NonCommercial license Permanent Image Page Printer Friendly View XB-IMG-123778